Raw racial tensions, live-streamed killings, strained trust between the police and communities they serve, and a presidential race that has scorched deep divides have the nation on edge and wondering if a leader will emerge from the chaos.

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Trump: Dallas police shooting an attack on the country

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Trump: Dallas police shooting an attack on the country01:10

The season of strife and tears took another bloody twist when five Dallas police officers were slain on Thursday as one tragedy rolled into another following police shootings of black men at traffic stops, gun rampages in cities like Chicago and an Orlando terror attack carried out by a radicalized gunman.

"This has been a long week for our country. It's been a long month for America. We have seen terrible, terrible senseless things," House Speaker Paul Ryan said on Friday, describing the latest scenes of horror and loss.

Political leaders, many like Donald Trump and Hillary Clinton with crucial elections on their minds, are getting used to tearing up their schedules in the wake of tragedies that shock the nation.

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Yet despite all the calls for unity, the prayers offered and the platitudes voiced, there are few signs yet that any candidate, lawmaker, law enforcement leader, or civil rights campaigner has mustered the trust and respect of voters needed to knit a mournful nation together and freshen the stale national debate on race and violence.

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President Obama reacts to Dallas shootings from Warsaw

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President Obama reacts to Dallas shootings from Warsaw02:32

The leadership vacuum raises questions about whether there will ever be a narrowing of the estrangement between African-American communities and police. It raises doubts that there will ever be room for compromise between gun-control advocates and Second Amendment absolutists or whether the criminal justice reform both Republicans and Democrats say they support will ever transit a Congress consumed by its own rancor.

The political scripts on Friday were certainly familiar after the tragedy in Dallas, which fused two festering issues that divide the nation -- easy access to firearms and discord over race -- into a night of terrible mayhem.

Democrats demanded more gun control and warned that America's racial agonies were far from over. Republicans bemoaned disrespect for the police and charged that liberal policies had doomed black America.

President Barack Obama once again saddled up for another somber address to the nation as mourner-in-chief.

Speaking Friday morning from the NATO summit in Poland, the President condemned the killings in Dallas as "vicious, calculated and despicable" and promised justice. "Today is a wrenching reminder of the sacrifices they make for us," Obama said of law enforcement officers.

As he has with other gun-related violence, Obama referenced the availability of guns in America.

"We also know when people are armed with powerful weapons, unfortunately, it makes attacks like these more deadly and more tragic," he said.

It was Obama's second speech on police and race in 12 hours. After landing in Warsaw, past midnight back at home, Obama rushed to his hotel and spoke about the deaths of two African-American men -- Alton Sterling of Louisiana and Philando Castile of Minnesota -- at the hands of police officers this week, each captured on heartrending cellphone footage.

"All of us Americans should be troubled by the shootings," Obama said, before laying out facts showing that African Americans are disproportionately more prone to be pulled over by, searched and shot by police.

But the first black President's long, complicated and often cautious conversation with Americans about race is running out of time.

Obama, the man who once famously said, "There is not a Black America, and white America and Latino America, and Asian America -- there is the United States of America," seemed to have changed his mind.

He appeared to address himself particularly to white America -- implicitly making a point that alienation and a sense of injustice permeating the African American community must be understood by everyone.

"This isn't a matter of us comparing the value of lives, this is recognizing that there is a particular burden being placed on a group of our fellow citizens," he said.

"And we should care about that. We can't dismiss it. We can't dismiss it."

Obama will cut short his European visit a day early and travel to Dallas next week, the White House said. And this time next year, Obama will be easing into a post-presidency which will grant him more freedom to speak explicitly about race. And the next President — Trump or Clinton -- will steer the nation's unresolved racial journey.

Both candidates reacted cautiously to the Dallas shootings, canceling campaign events and sending out tweets mourning the dead, aware that a moment of national peril loomed for them as a test of leadership.

But the campaign between two candidates who plumb historic depths in personal approval ratings promises to leave the next president with a disunited and disgruntled nation.

Trump's response to Dallas was especially notable, since he elected not to immediately politicize the latest tragedies, as he had the Orlando nightclub rampage last month. His temperate statement also bore the stamp of a political professional."We must restore law and order. We must restore the confidence of our people to be safe and secure in their homes and on the street," Trump said, also citing "senseless, tragic deaths of two motorists in Louisiana and Minnesota."

Trump later released a video using the same measured tone as his statement, saying the attack in Dallas had "shaken the soul" of the nation, and adding that the deaths of the two men in Louisiana and Minnesota also showed that America was a long way from making its people feel safe.

Clinton, in an interview with CNN's Wolf Blitzer, said the Dallas ambush was "absolutely horrific" and called on people to support the police. She proposed national guidelines for the use of force by officers and asked white Americans to put themselves in the shoes of African Americans.

"We just have to make up our minds that we are going to bring our country together," Clinton said. "This is much deeper even than these terrible killings. We have got to start once again respecting and treating each other with the dignity that every person deserves."

Clinton later said at the African Methodist Episcopal Convention in Philadelphia that "deep in our hearts, we know there is something wrong with our country."

"There is too much violence, too much hate, too much senseless killing, too many people dead who shouldn't be."

Other leaders also weighed in. Rep. John Lewis, a veteran of the civil rights movement wept in a Congressional Black Caucus news conference called to push for gun control.

Sen. Marco Rubio gave a glimpse of the leadership skills he touted in his unsuccessful GOP presidential campaign, saying "those of us who are not African American will never fully understand the experience of being black in America."

Former House Speaker Newt Gingrich, a possible vice presidential pick for Trump, said that "normal white Americans" don't understand "being black in America."

"It took me a long time, and a number of people talking to me through the years, to get a sense of this: If you are a normal white American, the truth is you don't understand being black in America and you instinctively underestimate the level of discrimination and the level of additional risk," Gingrich said on CNN Political Commentator Van Jones' Facebook Live stream.

But earlier Friday, Gingrich said on "Fox and Friends" that Obama never brought the nation together or "worked in the African-American community to make people feel better about themselves."

He was not the only one looking for culprits, reflecting the political reality of a polarized country.

On the same show, another Trump backer, Dr. Ben Carson, rebuked Obama for bringing up gun control in his remarks in Poland.

In another tweet, Iowa Republican Rep. Steve King said the Dallas shootings had their roots in "in first of anti-white/cop events illuminated by Obama."